If you wish to translate the wiki pages to your language but there is no button in the top right language links, you can ask per mail at email@example.com.
How to translate the wiki? It is possible to translate page by page, but it is not recommended for one simple reason, the maintenance will be one hell of a job! So do it differently, you can use the wiki to translate some pages that are useful to show off in your language of course, but you can also use the wiki frontpage to present the desktop environment in your language in a much simpler way. Put some links with cool localized content and so on. It's up to you, you can do anything!